BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a lock for locking the steering shaft or the gear rack of the steering gear or the output shaft of the transmission of a motor vehicle, said lock being fitted with a locking element displaceable to-and-fro between a locked and an unlocked position, and further with a control element rotated to-and-fro by means of a drive to axially displace a drive element cooperating with the locking element or to displace the locking element itself in either direction.
2. Description of the Related Art
A lock of this kind is known, wherein special steps are taken to assure that the locking element always shall move exactly the same distance to the locked or unlocked position but not farther, not even when the control element continues rotating, that is even when the drive is not stopped at the moment when the locking element has reached the locked or unlocked position. For that purpose the drive element or the locking element and the control element are configured coaxially, and said drive element or the locking element and the control element cooperate by means of
(a) two radial projections which are diametrically opposite the axis of rotation of the control element and are each displaceable as well as spring-loaded perpendicularly to the control element's axis of rotation,
(b) two bevels as well as two terminal surfaces which are situated in the same plane perpendicular to the control element's axis of rotation and can extend as far as next to either bevel, in such manner that the inner drive element or the inner locking element shall be commensurately axially displaced during the rotation of the outer control element in that direction in which the protrusions run on the bevels to the terminal surfaces, in order that, when the projections move from the bevels onto the terminal surfaces, they shall stand still and remain in the attained axial position until the control element is rotated in the opposite direction and the protrusions move on the bevels away from the terminal surfaces, whereby the drive element or the locking element shall be shifted axially in the opposite direction. These protrusions may be situated at the drive element or the locking element, and the bevels and the terminal surfaces may be located on the control element. The protrusions, if desired, may comprise two pins mounted in a common transverse borehole of the drive element or the locking element and may be biased by a common helical compression spring (see German Patent No. DE 44 36 326 C1).
The objective of the invention is to improve said known lock and in particular to reduce the number of parts, to simplify assembly and to lower manufacturing costs.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the lock of the invention are described below in relation to the attached drawings, wherein:
FIG. 1 is a top view in the direction of the arrow I of FIG. 2, the cover being off,
FIG. 2 is a longitudinal section view along line II—II in FIG. 1,
FIG. 3 is a longitudinal section view along line III—III of FIG. 2,
FIG. 4a is a longitudinal section view of the control element along line IV—IV in FIG. 1 seen in perspective and from above,
FIG. 4b is a longitudinal section view of the control element along line IV—IV of FIG. 1 seen in perspective and from below,
FIG. 5a is a longitudinal section view of the control element along line V—V of FIG. 1 seen in perspective and from above,
FIG. 5b is a longitudinal section view of the control element along line V—V of FIG. 1 seen in perspective and from below,
FIG. 6 is a cross-section of the control element along line VI—VI of FIG. 2,
FIG. 7 is a cross-section of the control element along line VII—VII of FIG. 2,
FIG. 8 is a cross-section of the control element along line VIII—VIII of FIG. 2,
FIG. 9 is a geometric development of the inner slot of the control element of FIG. 1 extending along the left of the drive element to the first terminal surface of the control element in accordance with another embodiment of the invention,
FIG. 10 is a geometric development similar to FIG. 9 in accordance with still another embodiment of the invention; and
FIG. 11 is a geometric development similar to FIG. 9 in accordance with still another embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
The lock shown in FIGS. 1 through 3 comprises a
housing 2 sealed by a
cover 1 and is used to lock the motor
vehicle steering shaft 3 shown in FIG. 3 by means of a
locking element 4 cooperating with a
locking bush 5 affixed to the
steering shaft 3. The
steering shaft 3 and the
locking bush 5 are enclosed by a
tubular case 6 to which the
housing 2 is affixed. The
locking element 4 is in the form a cross-sectionally rectangular stud and rests in an axially displaceable manner in a
duct 7 of matching cross-section of the
housing 2, the
longitudinal axis 8 of
said duct 7 orthogonally intersecting the longitudinal axis
9 of the
steering shaft 3.
The
locking element 4 is displaceable to-and-fro (i.e., extended and retracted) by a
drive element 10 between, on one hand a locked position where, by the
end 11 located away from the
drive element 10 engaging one of
several locking apertures 12 of the
locking bush 5, the
steering shaft 3 is made non-rotatable. On the other hand, when
locking element 4 is moved to the unlocked position shown in FIG. 3, the
locking element 4 no longer engages by its
end 11 any of the
locking apertures 12 of the
locking bush 5 and the
steering shaft 3 is thereby released.
The
drive element 10 is designed as a cylindrical bolt and is axially displaceable in a
cylindrical borehole 13 of the
housing 2, said
borehole 13 running coaxially with the
duct 7 receiving the
locking element 4. A
longitudinal slot 15 in the
housing 2 opens opposite the
narrow side 14 of the
locking element 4 Son the left in FIG. 2) into the
borehole 13. Opposite the
narrow side 16 of the
locking element 4, which is on the right in FIG. 2, the
borehole 13 also communicates with a
longitudinal slot 17 in the
housing 2. An external
radial protrusion 18 of the
drive element 10 enters the
longitudinal slot 15 and the
longitudinal slot 17 receives a radially extending
protrusion 19 of the
drive element 10.
The
end 20 of the
locking element 4 located away from the
steering shaft 3 is received in a
blind hole 21 of the
drive element 10, said
blind hole 21 has a cross-section corresponding to the rectangular cross-section of the
locking element 4. Said
end 20 is fitted with a
cross-pin 22 running perpendicularly to the two
wide sides 23,
24 of the
locking element 4. The two ends
25,
26 of said
cross-pin 22 project from the
locking element 4 and enter two lateral
elongated slots 27,
28 of the
drive element 10. A
helical compression spring 31 is mounted between the
end 20 of the
locking element 4 and an
annular recess 29 in the
bottom 30 of the
blind hole 21 of the
drive element 10 and biases the two projecting
ends 25,
26 of the
cross-pin 22 of the
locking element 4 against the
ends 32,
33 near the
steering shaft 3 of the two
elongated slots 27,
28 of the
drive element 10. The
locking element 4 is able to enter the
blind hole 21 of the
drive element 10 against the force of the
helical compression spring 31 when—during the displacement of the
locking element 4 by the
drive element 10 into the locked position—none of the
locking apertures 12 of the
locking bush 5 secured to the
steering shaft 3 is aligned with the
locking element 4 so as to receive its
free end 11.
A
control element 35 driven in reversible directions by an
electric motor 34 that when rotated in one direction axially displaces the
drive element 10 into the position of FIGS. 2 and 3 to drive the
locking element 4 into the unlocked position and when rotated in the opposite direction, axially displaces the drive element to
10 in the opposite direction to drive the
locking element 4 into the locked position. The
control element 35 is configured coaxially with the
drive element 10 which it encloses, and furthermore rests in rotatable manner in the
housing 2 about the common
longitudinal axis 8 of the locking-
element duct 7 and the drive-
element borehole 13 between an
annular surface 36 of the
housing 2 coaxial with said
longitudinal axis 8 and an
annular surface 37 of the
cover 1 coaxial with this
longitudinal axis 8. Said
control element 35 is formed as a worm gear fitted with
external teeth 38 engaged by a
drive worm 40 affixed to the
output shaft 39 of the
electric motor 34. This
electric motor 34 may be a 12 VDC motor the direction of rotation of which is reversed by a reversal of applied electrical power and which does not move if it is unpowered.
The
external control element 35 cooperates with a
cylindrical cross-pin 41 of the
inner drive element 10 supported in an axially displaceable manner in a cylindrical
transverse borehole 42 of the
drive element 10. For that purpose the
control element 35 is fitted with two helical
inner channels 43,
44 and two
plane terminal surfaces 45,
46 each lying perpendicular to the axis of
rotation 8 of the
control element 35. The
channels 43,
44 extend between the
terminal surfaces 45,
46 each of which is bounded by a
side ramp 47 and
48 respectively of specified design.
As shown in particular detail in FIGS. 4
a through
5 b, the two
inner channels 43,
44 of the
control element 35 extend along that
cylindrical borehole 49 of the
control element 35 which receives the
drive element 10. The
first channel 43 is shown in FIG. 1 to extend to the left of the
drive element 10 to the
first terminal surface 45 of the
control element 35, away from the
steering shaft 3, and at a first end
50 (FIG. 4
a) merges into the
first terminal surface 45. At a second end
51 (FIG. 5
b) thereof, the
first channel 43 merges into the
second terminal surface 46 of the
control element 35 which is closer to the
steering shaft 3. The
second channel 44 which in FIG. 1 runs on the right of the
drive element 10 to the
first terminal surface 45 merges at a first end
52 (FIG. 5
a) into the
first terminal surface 45 and at a second end
53 (FIG. 4
b) into the
second terminal surface 46.
The
vertical side ramp 47 of the
first terminal surface 45 of the
control element 35 extends from the
bottom 54 of the
first channel 43 of the
control element 35 outwardly past and up to a given
distance 55 from the
second channel 44 of the
control element 35 toward the
borehole 49 of the
control element 35 that receives the
drive element 10 and in particular the
end 56 that merges into the borehole
49 (FIGS. 4
a,
5 a). Again, the
vertical side ramp 48 of the second
terminal surface 46 of the
control element 35 extends from the bottom
54 of the
first channel 43, past and outside and at a given
distance 57 from the
second channel 44 toward the borehole
49 where it merges at the
related end 58 in the borehole
49 (FIGS. 4
b,
5 b).
For manufacturing, the two
openings 59,
60 of the
first channel 43 of the
control element 35 on the first
terminal surface 45 of the control element
35 (FIGS.
4 a,
4 b) and respectively on the second
terminal surface 46 of the control element
35 (FIGS. 5
a,
5 b), each comprise an
end face 61, on the side away from the first
terminal surface 45 and opposite the
first end 50 of the
first channel 43 and respectively an
end face 62 on the side away from the second
terminal surface 46 and opposite the
second end 51 of the
first channel 43, each end face
61 or respectively
62 being situated in a plane passing through the axis of
rotation 8 of the
control element 35.
FIGS. 6 through 8 show the described design of the
control element 35.
The described motor-vehicle steering lock operates as follows:
When the locking
element 4 is in the locked position, the
drive element 10 which is located within
borehole 13 of
housing 2 rests against a
stop 63 firmly affixed to the housing, that is the
drive element 10 rests with its
terminal face 64 enclosing the
locking element 4 at the bottom of the
borehole 13 of the
housing 2, said bottom constituting the
stop 63. The cross-pin
41 of the
drive element 10 extends, namely the two ends
65,
66 of the cross-pin
41 that project from the
transverse borehole 42 of the
drive element 10, extend directly along the second
terminal surface 46 of the
control element 35 outside the path along which the
end face 62 of the
opening 60 of the
first channel 43 of the
control element 35 associated with the second
terminal surface 46 moves when the
control element 35 is being rotated.
The
electric motor 34 is turned on and thereupon rotates the
drive worm 40 in the direction of the
arrow 68 and the
control element 35 is rotated in the direction of the
arrow 69 in FIG. 1 to displace the
locking element 4 axially out of the locked position and the
drive element 10 axially out of the above discussed axial position in the direction of the
arrow 67 of FIGS. 2,
3 and then into the unlocked position and into the corresponding axial position of FIGS. 2,
3 respectively. As a result, the two ends
65,
66 of the cross-pin
41 of the
drive element 10 that project from the
transverse borehole 42 of the
drive element 10 depart from the second
terminal surface 46 of the
control element 35 and enter the
helical channels 43,
44 in order to move from the second ends
51,
53 of the
channels 43,
44 to their first ends
50,
52. In the corresponding angular position of the
control element 35, the
drive element 10 has reached that axial position wherein the
locking element 4 assumes the unlocked position and at which the
drive element 10 also shall be maintained even if the
control element 35 continues rotating in the direction of the
arrow 68. Consequently, the locking
element 4 in such a case will remain in the unlocked position.
This is so because the two ends
65,
66 of the cross-pin
41 of the
drive element 10 which both project from the
transverse borehole 42 of the
drive element 10 pass onto the first
terminal surface 45 of the
control element 35 in order to move along the first
terminal surface 45 away from the first ends
50,
52 of the
channels 43,
44 of the
control element 35. During this movement the upper
cross-pin end 66 shown in FIG. 1 comes to rest against the
side ramp 47 of the first
terminal surface 45 at the
point 70, so that, as the
control element 35 continues rotating in the direction of the
arrow 69, the
cross-pin end 66 is moved into the
transverse borehole 42 of the
drive element 10 by the segment of the
side ramp 47, which extends between the
point 70 and the
end 56 of the
side ramp 47. Thus the lower
cross-pin end 65 shown in FIG. 1 shall be displaced sufficiently out of the
transverse borehole 42 of the
drive element 10 to move on the first
terminal surface 45 over the
second channel 44 and then in turn will be moved by the
side ramp 47 into the
transverse borehole 42 of the
drive element 10, namely by the side ramp segment between the
first end 52 of the
second channel 44 and the
end 56 of the
side ramp 47, the other
cross-pin end 66 moving out of the
transverse borehole 42 of the
drive element 10 onto the first
terminal surface 45. As long as the
control element 35 rotates in the direction of the
arrow 69, the cross-pin
41 of the
drive element 10 is forced to stay on the first
terminal surface 45 of the
control element 35, and as a result the
drive element 10 remains in the axial position shown in FIGS. 2,
3. In this axial position a
cup spring 72 mounted between the
cover 1 of the
housing 2 and the
end 71 of the
drive element 10 at the side of said
cover 1 presses the cross-pin
41, i.e. its ends
65,
66 projecting out of the
transverse borehole 42 of the
drive element 10, against the first
terminal surface 45 and out of the path along which the
end face 61 of the
opening 59 of the
first channel 43 of the
control element 35 associated with the first
terminal surface 45 is moving when the
control element 35 is being rotated. The locking
element 4 correspondingly remains in the unlocked position shown in FIGS. 2,
3.
Only when the
electric motor 34 runs in the opposite direction and the
drive worm 40 as well as the
control element 35 are rotated by it in the opposite direction, namely when the
drive worm 40 is rotated in the direction of the
arrow 73 and the
control element 35 is rotated in the direction of the
arrow 74 of FIG. 1, will the locking
element 4 be displaced out of the unlocked position and the
drive element 10 out of the corresponding axial position of FIGS. 2,
3 in the direction of the
arrow 75 of FIGS. 2,
3, axially into the locking position and respectively into the corresponding axial position. This displacement begins as soon as the two ends
65,
66 of the cross-pin
41 of the
drive element 10 projecting from the
transverse borehole 42 of the
drive element 10 have left the first
terminal surface 45 of the
control element 35 and enter the two
helical channels 43,
44 of the
control element 35 at the first ends
50,
52 of said
channels 43,
44. This displacement ends as soon as the cross-pin ends
65,
66 leave the
channels 43,
44 at their second ends
51,
53 and move onto the second
terminal surface 46 of the
control element 35. Then, the
control element 35 may still be further rotated in the direction of the
arrow 74 without imparting any motion to the
drive element 10 and the
locking element 4 because the
side ramp 48 of the second
terminal surface 46 runs similarly to the
side ramp 47 of the first
terminal surface 45 of the
control element 35 and causes a similar axial displacement of the cross-pin
41 of the
drive element 10 in the
transverse borehole 42 thereof.
Accordingly, the
electric motor 34 is not required to stop abruptly when the locking
element 4 reaches the unlocked or locked position and when the
drive element 10 has reached the particular corresponding axial position. Rather, the
motor 34 may continue to run in the direction of the
arrow 68 or of the
arrow 73 and drive the
control element 35 through any additional angle in the direction of the
arrows 69 or
74 without causing displacement of the
locking element 4 and of the
drive element 10, and without the locking
element 4 leaving the unlocked or locked position and without the
drive element 10 leaving the specific corresponding axial position.
It is not required that the
electric motor 34 rotates the
control element 35 only relatively slowly. Instead the above described cooperation of the
control element 35 and the
locking element 4 by means of the
drive element 10 shall reliably take place when the
control element 35 is rotated relatively fast.
FIGS. 9 through 11 diagrammatically show various designs of the two
openings 59,
60 of the
first channel 43 and the two
terminal surfaces 45,
46 of the
control element 35 as well as of the support for the
drive element 10 in the
housing 2.
As shown in FIG. 9, the
first channel 43 of the
control element 35 runs on one hand as far as the
first end face 76 of the
control element 35 resting against the
annular surface 37 of the
cover 1 of the
housing 2 and on the other hand as far as the
second end face 77 of the
control element 35 resting against the
annular surface 36 of the
housing 2. Thus, the
opening 59 of the
first channel 43 associated with the first
terminal surface 45 of the
control element 35 is bounded by a sharp
linear edge 78 on that side which is away from the first
terminal surface 45 and opposite the
first end 50 of the
first channel 43, and the
opening 60 of the
first channel 43 associated with the second
terminal surface 46 of the
control element 35 is bounded, on the side away from the second
terminal surface 46 and opposite the
second end 51 of the
first channel 43, also by a sharp,
linear edge 79. The first
terminal surface 45 is situated a
distance 80 from the
first end face 76 of the
control element 35, said
distance 80 matching the diameter of the cross-pin
41 of the
drive element 10. Again, the
distance 81 between the second
terminal surface 46 and the
second end face 77 of the
control element 35 substantially corresponds to the diameter of the cross-pin
41 of the
drive element 10. The
drive element 10 is supported in the
housing 2 solely by means of the cross-pin
41.
When the
control element 35 rotates in the direction of the
arrow 69 of FIG. 9, and the cross-pin
41 of the
drive element 10 projects between the second
terminal surface 46 of the
control element 35 and the
annular surface 36 of the
housing 2, the cross-pin
41 located at the
opening 60 of the
first channel 43 of the
control element 35 and associated with the second
terminal surface 46 enters the
first channel 43 in order to move therein as far as the
opening 59 associated with the first
terminal surface 45 of the
control element 35. Thus the cross-pin
41 moves at the
first end 50 of the
first channel 43 onto the first
terminal surface 45 which moves past the cross-pin
41 in the direction of the
arrow 69. As soon as the
point 70 of the
side ramp 47 of the first
terminal surface 45 moves past the cross-pin
41, the latter is displaced by the
side ramp 47 from the plane of the drawing of FIG. 9 toward the observer until the
end 56 of the
side ramp 47 moves past the cross-pin
41.
If thereupon the
control element 35 rotates in the opposite direction, that is the direction of the
arrow 74 of FIG. 9, then the cross-pin
41 shall enter the
first channel 43 at the
opening 59 associated with the first
terminal surface 45 of the
control element 35 in order to move therein as far as the
opening 60 associated with the second
terminal surface 46 of the
control element 35 and to move at its
second end 51 onto the second
terminal surface 46 which then shall move past the cross-pin
41 in the direction of the
arrow 74. As soon as the
point 82 of the
side ramp 48 of the second
terminal surface 46 corresponding to the
point 70 of the
side ramp 47 of the first
terminal surface 45 has passed the cross-pin
41, this cross-pin
41 is displaced by the
side ramp 48 from the plane of the drawing of FIG. 9 toward the observer until the
end 58 of the
side ramp 48 passes the cross-pin
41.
The embodiments of FIGS. 10,
11 only differ from that of FIG. 9 in that the two
openings 59,
60 of the
first channel 43 of the
control element 35, respectively comprise the above-described
end face 61 and
62 and in that the
drive element 10 is supported by a
compression spring 83 on the
cover 1 of the
housing 2 and a
compression spring 84 on the
housing 2, or cooperates with a
stop 85 at the
cover 1 and a
stop 86 at the
housing 2. The compression springs
83,
84 press the cross-pin
41 of the
drive element 10 respectively against the first
terminal surface 45 of the
control element 35 and away from the
end face 61 of the associated
opening 59 and against the second
terminal surface 46 of the
control element 35 and away from the
end face 62 of the associated
opening 60. The stops
85,
86 keep the cross-pin
41 of the
drive element 10 respectively at the first
terminal surface 45 and away from the
end face 61 of the associated
opening 59, and at the second
terminal surface 46 away from the
end face 62 of the associated
opening 60. In the embodiment of FIG. 10, the end faces
61,
62 of the
openings 59,
60 are offset a corresponding distance from the
ends 50,
51 of the
first channel 43 toward the
ends 56,
58 of the side ramps
47,
48 of the terminal surfaces
45,
46 of the
control element 35. As regards the embodiment of FIG. 11, the end faces
76,
77 of the
control element 35 each run at a correspondingly
larger distance 80′ and
81′ from the first
terminal surface 45 and from the second
terminal surface 46 of the
control element 35.
The above description is of exemplary embodiments of the invention only and the invention is to be regarded as defined in the following claims.